GB2598164A

GB2598164A - Connection of a drive unit to wheel

Info

Publication number: GB2598164A
Application number: GB2014787.2A
Authority: GB
Inventors: Rupert Joseph Darwood Alastair
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-18
Filing date: 2020-09-18
Publication date: 2022-02-23
Anticipated expiration: 2040-09-18
Also published as: JP2023538342A; GB2598164B; EP4200150A1; IL300742A; AU2021328680A9; GB202014787D0; GB202013400D0; WO2022038207A1; GB202012843D0; US20230303209A1; MX2023001913A; CN116323381A; TW202220897A; AU2021328680A1

Abstract

A drive unit is connected to a wheel 20 to enable the drive unit to drive rotation of the wheel, particularly of a bicycle. The apparatus comprises a drive member 10, a mounting member 12, a drive element 16 and rotation preventing means 36, 38. The drive member 10 is mounted to the wheel 20. The mounting member 12 is mounted on the drive member 10 and rotatably independent of the drive member 10 about the central axis. The drive element 16 has a drive element axis fixedly disposed relative to the mounting member 12, and is coupled to a motor 18 such that as to drive rotation of the drive element 16 about its axis. The rotation preventing means restrains rotation of the mounting member 12 about the central axis ensuring that the rotation of the drive element 16 drives rotation of the drive member 10 and hence the wheel 20. The Drive member 10 may be a disc brake rotor.

Description

CONNECTION OF A DRIVE UNIT TO A WHEEL

Field of the Invention

The present invention relates to apparatus for connecting a drive unit to a wheel, particularly but not exclusively to a bicycle wheel. The present invention further relates to a wheel with such apparatus mounted on the wheel. The present invention yet further relates to a method of mounting parts to a hub for connecting a drive unit to the hub, particularly but not exclusively where some of the parts are mounted in a place of a conventional disc brake rotor.

Background to the Invention

Electric drive systems that may be fitted to conventional bicycles to assist riders in cycling are well known. A known document, US9359040, discloses such a drive system in which a disc rotor for a disc braking system is adapted to include teeth with which a gear may engage. The gear is mounted on a device, which is in turn mounted on a chainstay of a bicycle at a mounting point that is conventionally used for mounting of a brake calliper mechanism of the disc braking system, and coupled to an electric motor so that the gear can be driven by the electric motor. The disc rotor is therefore used in driving rotation of a wheel, as well as in braking.

Another known document, DE102016113572, discloses as an electric motor configured to drive rotation of a rotor of a disc braking system. In this case, a gear is affixed to the rotor and the gear is coupled to a drive shaft of an electric motor by means of a chain. The rotor is also thus used to drive rotation of a wheel, as well as for braking. The motor is mounted on a frame of the bicycle.

In both cases, the drive systems are bulky and highly visible in a congested region of a bicycle. As a result, these systems may only be fitted to specific bicycles with modification of frame mounted components. In addition, these drive systems require specific mounting features on bicycle frames, which may not be present on all such frames. It is an object of the present invention to improve on such systems.

Summary of the Invention

According to the present invention, there is provided apparatus for connecting a drive unit to a wheel to enable the drive unit to drive rotation of the wheel about a central axis of the wheel, comprising: a drive member for mounting to the wheel such that rotation of the drive member about the central axis drives rotation of the hub about the central axis; a mounting member mounted on the drive member and rotatably independent of the drive member with respect to the central axis; a drive element having a drive element axis that is fixedly disposed in relation to the mounting member, and for coupling to the drive unit such that the drive unit can drive rotation of the drive element about the drive element axis; preventing means for preventing rotation of the mounting member about the central axis; wherein the drive member includes coupling means for coupling with the drive element, so that the rotation of the drive element drives rotation of the drive member, wherein the drive member has a first surface for facing away from the wheel when the drive member is mounted on the wheel, and wherein the coupling means and the drive element are at least partially located in a recessed region in the first surface.

Thus, parts may usefully be partially or wholly attached to and/or mounted on and/or carried by the mounting member. This eliminates or reduces need for parts to be mounted on a frame.

The mounting member may be carried by the drive member.

There may also be provided a wheel comprising such apparatus, the apparatus being mounted on a hub of the wheel.

According to the present invention, there is further provided a method of connecting a drive unit to a wheel to enable the drive unit to drive rotation of the wheel about a central axis of the wheel, comprising: mounting the apparatus set out above onto a wheel; and coupling the drive element to the drive unit.

Some preferred and/or optional features and/or steps are set out in the dependent claims.

Brief Description of Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which: Figure 1 is a perspective view of a bicycle wheel with a drive system in accordance with an embodiment of the present invention fitted; Figure 2 is a perspective view like Figure 1, but with the drive system exploded; Figure 3 is another exploded view, like Figure 2, from a different perspective; Figure 4 is a perspective close-up view of elements of the embodiment, with some elements shown exploded; Figures 5 and 6 are close-up perspective views of the drive system when fitted; Figures 7 and8 are views of a bicycle with the fitted drive system; Figures 9 and 10 are views of a bicycle with the fitted drive system and electric motor and mounting apparatus removed; Figure 11 is a first side view of a drive member of the drive system; Figure 12 is a perspective view of the second side of the drive member; Figure 13 is a perspective view of a mounting member of the drive system; and Figure 14 is a side view of the mounting member; Figure 15 is a perspective view of a drive member in accordance with an alternative embodiment; Figures 16 and 17 are perspective views of parts of a drive system in accordance with another embodiment including a pulley and belt assembly.

Detailed Description of Embodiments

Embodiments of the invention relate to apparatus for a drive system for driving rotation of a wheel, in particular to apparatus for connecting a drive unit of the drive system to the wheel. In the embodiments described below, the wheel is that of a bicycle, although embodiments of the invention are not limited to such. For example, the drive system may be used to drive rotation of a wheel of a wheelchair or a golf trolley. The drive system is typically for use to supplement human power driving a wheel, for example pedalling action, but may be used as an alternative to human power or to supplement means other than human power used for driving a wheel.

Referring to Figures 1 to 14, in an embodiment the drive system includes a drive member 10, a mounting member 12, an annular bearing assembly 14, a rotation prevention assembly 15, a drive element in the form of a pinion gear 16, and the drive unit in the form of an electric motor 18. The drive system is mounted onto a rear wheel 20 of a bicycle. The wheel includes a hub 22 and a cassette 24. An axle (not shown) extends through the hub 22 and the cassette 24 about which the hub rotates. The drive system may alternatively be mounted on a front wheel of a bicycle.

Embodiments are also not limited to use with an electric motor. Embodiments may be implemented with any device from which torque can be transferred to the drive element. For example, embodiments may couple to a drive shaft of a motor in the form of an internal combustion engine.

The wheel has an axis about which the wheel rotates and the term "central axis" shall be construed accordingly. The term "hub axis" is to be construed as the same axis.

The drive member 10 is for location on the hub 22 where a conventional disc rotor is conventionally mounted and, accordingly, when located there a conventional disc rotor is absent. When so located, the drive member 10 has a first side that faces outwardly away from spokes of the wheel and a second side that faces the spokes. As best seen in figures 11 and 12, the drive member 10 includes a mounting portion, an annular back plate 10c, an internal gear 10d, a second cylindrical wall 10e and an annular braking rotor portion 101. The mounting portion includes a hub mounting plate 10a. The mounting portion also includes a first cylindrical wall 10b having a cylindrical outer circumferential surface. The cylindrical wall 10b extends at a first end thereof from the hub mounting plate 10a away from spokes of the wheel. The annular back plate 10c extends from a second end of the first cylindrical wall 10b radially with respect to the hub axis. The second cylindrical wall be extends from the annular back plate 10c away from spokes of the wheel at a first end thereof. The first and second cylindrical walls 10b, be are both coaxial with the hub 22. The internal gear 10d is mounted on the annular back plate 10b and on an internal surface of the second cylindrical wall 10e, facing the outer surface of the first cylindrical wall 10b. In some embodiments, the internal gear 10d is mounted on the annular back plate 10b or on an internal surface of the second cylindrical wall 10e The drive member 10 may be formed of a single piece of material. In variant embodiments the drive member 10 may be formed of more than one piece of material. In some variants, the internal gear 10d may be formed separately and fixed to a rest of the drive member 10 by welding or by any suitable manner of affixing, or in some embodiments by locking of portions suitably adapted for locking. In some variants, the braking rotor portion 10f may be formed separately and fixed to the rest of the drive member 10 by welding or any suitable manner of affixing, or in some embodiments by locking of portions suitably adapted for locking. The drive member 10 may be otherwise formed of different parts that are fixed together in other variant embodiments. Making the drive member 10 of multiple parts facilitates different parts being made of different materials.

The hub 22 is of a conventional type and includes a conventional disc rotor mounting means configured to enable mounting of a matching conventional disc rotor configured for mounting on the disc rotor mounting means. In the embodiment shown, the disc rotor mounting means includes a mounting plate fixed to and extending radially from the rest of the hub 22 (although the mounting plate is obscured in the figures), the mounting plate being according to a conventional six bolt design. A conventional disc rotor configured for the six bolt design may be securely bolted to the mounting plate and used in a conventional disc braking system. . When the conventional disc rotor is mounted on the mounting plate, relative rotation of the disc rotor and the hub 22 is thus prevented so the disc rotor and the hub 22 rotate synchronously and calliper action on the disc rotor by a calliper mechanism brakes rotation of the wheel.

In the drive member 10, the hub mounting plate 10a has holes in accordance with the six bolt design, like a conventional disc rotor. The drive member 10 can thus be securely bolted to the mounting plate in place of the conventional disc rotor. A conventional disc rotor may be removed from the mounting plate to enable this and to permit the drive member 10 to be located on the hub 22. The drive member 10 may also be removed from the mounting plate and replaced if it wears out. The bolting of the drive member 10 to the mounting plate prevents relative rotation of the drive member 10 and the hub is, such that the drive member 10 and the hub 22 rotate synchronously.

Hubs of other types are known that do not use a mounting plate with a six bolt design for mounting of a disc rotor on the hub, but instead use alternative attaching means. The drive member 10 may in variant embodiments be configured to attach to such hubs using an appropriate alternative attaching means for that hub. For example, a hub and conventional disc rotor (not shown) may use a splined arrangement, in which the hub includes a male spline. The conventional disc rotor includes a corresponding female spline and the drive member (e.g. the hub mounting plate 10a thereof) may be configured with the same female spline. The male and female splines are configured to mate, thereby to permit the conventional disc rotor to be located on the hub and removed from the hub by relative axial movement. A lock ring may be conventionally used to lock a splined disc rotor in place to prevent the relative axial movement and the same may be used to lock such a drive member in place. In this example, the splined arrangement prevents relative rotation of the drive member and the hub so the drive member and the hub rotate synchronously.

The drive member 10 and in particular the hub mounting plate 10a and/or annular back plate 10c thereof may in variant embodiments be adapted for use with other designs of hub using the alternative attaching means appropriate for that other design, such that the drive member 10 is fixedly mounted to the hub. Embodiments of the invention are not limited to use with any particular design of hub or wheel.

The braking rotor portion 10f extends radially from the second cylindrical wall 10e. The braking rotor portion 10f is located in the same space as an annular outer portion of a conventional disc rotor and has the same circular outer diameter or a circular outer diameter that can be accommodated by the disc braking system. The drive member 10a is configured so that the disc braking system remains functional after the disc rotor is replaced with the drive member and a calliper of a disc braking system can press against the braking rotor portion 10f to cause the braking. The thickness of the braking rotor portion 10a is such that the braking rotor portion can function with the disc braking system and may be the same as that of a rotor disc, for example 1.7mm.

The hub mounting plate 10a and the annular braking rotor portion 10f are planar. They provide the drive member 10 with a surface that, when the drive member 10 is mounted on the hub, faces outwardly away from spokes of the wheel. It is not essential that these parts are planar to all embodiments. The first and second cylindrical walls 10b, be and the annular back plate 10c provide an annular recessed region 26 extending around the central axis of the hub 22.

When mounted on a wheel, an open side of the recess 26 faces away from the wheel. The annular recessed region 26 is sufficiently wide in diameter (diameter being indicated at A-A in Figure 11) as to accommodate the pinion gear 16 and the internal gear 10d, but not so wide as to interfere with operation of the braking rotor portion 10f where the braking rotor portion 10f enters the calliper. The drive member 10 may have a maximum depth of only 2-3mm, although there is typically space at the back wheel of a bicycle for the drive member 10 to be deeper, for example where a deeper annular recess is wanted.

There is typically little space between the outward facing side of a conventional disc brake rotor, that is, the side facing away from the wheel, and the frame of a bicycle. The annular recessed region 26 usefully provides space for the pinion gear 16 and the internal gear 10d to be located so that a drive shaft for the pinion gear 16 can extend away from the wheel. Notably, a system described in a known patent publication, DE102016113572B3, describes location of gears between a device and a wheel in an attempt to avoid the issue of space, but has various disadvantages over provision of the recessed region 26 to provide space for the pinion gear 16 and the internal gear 10d.

In some embodiments, the pinion gear 16 and the internal gear may only be partially mounted in the recessed region 26, and may extend through the open side of the recessed region 26 away from the wheel. It may also be noted that the drive member 10 need not be configured to provide such an annular recessed region. Other configurations are possible. For example, the drive member may be substantially planar and the internal gear may be mounted on the drive member, to project from it. However, in this case the internal gear and the mounting member 12 would have to be very thin to prevent contact with the frame.

The annular back plate 10c usefully protects the internal gear 10d and the pinion gear 16 from dirt, and preferably seals the recess 26 between the recess 26 and the wheel. Usefully, the drive member 10, including the annular back plate 10c, and the mounting member 12 together enclose the pinion gear 16 and the internal gear 10d, preventing ingress of dirt. In variant embodiments the annular back plate 10c and/or the mounting member 12 may have spaces therein; although dirt may ingress through such spaces weight of parts may be reduced.

As best seen in Figure 13, the mounting member 12 comprises a cylindrical portion 12a located in the recessed region 26 and an annular mounting plate 12b extending outwardly from the cylindrical portion 12a with respect to the hub axis. The annular bearing assembly 14 is located in the recessed region 26 between the cylindrical portion 12a and the first cylindrical wall 10b, which has a cylindrical outer surface. The cylindrical portion 12a is fixed to an outer surface of the bearing assembly 14 and the inner surface of the bearing assembly is fixed to the cylindrical outer surface. The mounting member 12 is thus mounted on the first cylindrical wall 10b via the bearing assembly 14, and the drive member 10 can rotate freely with respect to the mounting member 12 about the hub axis and vice versa. The annular mounting plate 12b locates flush against an outward facing side of the drive member 10.

The mounting member 12 has an annular step 28 formed in it, facing away from the wheel 20 and extending circumferentially around the hub 22. The drive system includes a circlip 30 located in an annular space provided by the annular step 28, the circlip 30 gripping the exterior of the first cylindrical wall 10b. The circlip 30 prevents lengthwise movement of the mounting member 12 with respect to the hub axis, but permits rotational movement. As will be appreciated, the annular step 28 is provided for compactness.

The mounting plate 12b has three holes 32a-c in it. A drive shaft 34 of the motor 18 extends through a first of these holes 32a and fixedly mates with a shaft of pinion gear 16 which resides within the recessed region 26. The first hole 32a is provided with a recessed opening in which a bearing 107 is located and through which the shaft of pinion gear 16 also extends. A circlip 108 clamps onto the pinion gear shaft and secures the pinion gear 16 within hole 32a within the mounting member 12. The shaft of the pinion gear 16 is in a fixed disposition relative to the mounting member 12. An axis of the pinion gear 16 is parallel to the hub axis. In variant embodiments, the pinion gear 16 may be otherwise mounted to the mounting member 12 or directly mountable to the drive shaft of the motor 18.

A rotation prevention assembly 15 comprises an arm 36, a stop element 38, stop element mounting bolts 40 and a plurality of motor mounting bolts 44. The stop element 38 is mounted on an end of the arm 36 by means of a mounting hole therein and the stop element mounting bolt 40. The arm 36 includes two holes 33a, 33b that align with holes 32b, 32c, which are threaded, in the mounting plate 12b. The rotation prevention assembly is mounted on the mounting plate 12b by means of bolts 41 each extending through respective aligned holes 32b, 32c, 33a, 33b. In variant embodiments, the rotation prevention assembly is otherwise mounted to the mounting member 12 by alternative fixing means.

The pinion gear 16 (or a shaft thereof) may have a keyway by which a drive shaft of the motor 18 can detachably connect to the pinion gear 16. In this way, when the motor 18 is mounted to the rotation prevention assembly by means of motor mounting bolts 44, the motor shaft passes through hole 45 and the hole 32a and is synchronously connected to the shaft of pinion gear 16 which is, in turn, secured to mounting plate 12b by the bearing 107 and the circlip 108.

The arm 36 and the stop element 38 are shaped for the stop element 38 to abut a chainstay of the bicycle when the mounting member 12 rotates, which prevents further rotation of the mounting member 12 and all parts mounted on the mounting member 12, including the rotation prevention assembly 15 and the motor 18. Where the drive system is mounted on a front wheel of a bicycle for driving rotation of the front wheel, the stop element 38 instead abuts a fork. In variant embodiments where the electric drive system is implemented on a wheel other than on a bicycle wheel, the stop element 38 may abut a frame member on which the wheel is mounted or any other frame member or object that moves translationally with the wheel but not rotationally.

The pinion gear 16 is mounted on the end of the drive shaft 34 in the annular recess 26 and engaged with the internal gear 10d. The arm 36 has four motor mount holes 42 therein. The motor 18 is mounted on the arm 36 by means of four bolts 44 that extend though the four motor mount holes 42 and engage in threaded holes (not shown) in a body of the motor 18.

The motor 18 is thus fixedly mounted on and carried by the rotation prevention assembly 15. The motor 18 may include a battery, or alternatively be coupled to a battery located elsewhere on the bicycle.

The electric drive system need not be configured with parts replacing the disc rotor of an electric braking system. In alternative embodiments, the drive member 10 may be otherwise mounted on the hub so as to drive rotation of the hub. Embodiments are not limited to any particular way in which this is done. In some embodiments, the drive member may be mounted on a cassette in place of one or more sprockets. Where the drive member is not to replace a conventional rotor disc, the annular braking rotor portion 10f serves no purpose and can thus be omitted.

The drive member 10, the mounting member 12, the anti-rotation assembly 15, the pinion gear 16 and various bolts may be made from steel or another suitable material. The stop element 38 is preferably formed of a material sufficiently soft as to avoid damage to the chainstay, for example a plastic material or a hard material with a soft, e.g. rubber, outer. The other parts may be made from other materials including metals and plastics, as would be apparent to the skilled person.

The stop element 38 and/or the arm 36 may be configured to be adjustable in length, for example, by means of adjustment screws or varying stop element sizes, so as to ensure acceptable contact with the frame chainstay.

In operation, the motor 18 drives rotation of the pinion gear 16. The pinion gear 16 drives rotation of the internal gear 10d, thus driving rotation of the driving member 10. The driving rotation of the internal gear 10d in one direction results in force on the mounting member 12 urging rotation in the opposite direction. The mounting member 12 thus pivots until the stop element 38 abuts against the chain stay or other fixed portion of the bicycle frame.

The motor 18 may be removed together with the rotation prevention assembly by removal of bolts 41. The drive shaft of the motor 18 may simply be withdrawn from the pinion gear 16. The motor 18 may be reattached in a reverse operation.

In a further embodiment, the stop element 38 may be configured to mount to the bicycle seat stay (not shown). As the seat stay is reached by pivoting in the opposite direction, in use, stop element 38 is not driven into the seat stay; rather, it is pulled away from the seat stay thus the stop element 38 is mountable to the seat stay by means of a clamp or elastic or other nonelastic securing mechanism configured to prevent separation.

In a variant embodiment, the stop element 38 is absent and instead an attachment is provided securing the arm 36 to the chainstay. The attachment may, for example, be in the form of a clamp or strap around the chainstay, also attached to the arm 36 by a bolt or other suitable means. It is notable that the arm 36 is not required for mounting of the motor 18, but rather the rotation prevention assembly 15 including the arm 36 counters the resultant torque generated by the mounted motor 18. The arm 36 may in a variant embodiment be mounted on the mounting member 12 independently of the motor 18. As described below, the motor 18 need not be carried by the mounting member 12. The stop element 38 and optionally the arm may alternatively be replaced with other means for attaching the mounting member 12 to the chainstay or other frame member to prevent rotation of the mounting member 12. For example, such attaching means may be in the form of straps with hook and loop material.

In a variant embodiment, the motor 18 and any associated housing (not shown) may act as a stop element. In this embodiment, the motor and associated housing may protrude longitudinally away from the wheel with respect to the central axis of the wheel a distance that is further than the chainstay. In this way rotation of mounting element 12 will cause the motor and associated enclosure to directly impact the chainstay. Motor enclosure hardware may be adapted to facilitate acceptable contact with the chainstay, for example additionally comprising securing means such as a clamp or elastic. In this embodiment, the motor may be directly attached to mounting plate 12b without need of rotation prevention assembly 15.

In a variant embodiment, the motor 18 is not attached to the arm 36 by the bolts 44. Instead, the motor 18 is attached using a quick release mechanism, so that the motor 18 can be quickly detached and reattached. In an alternative variant embodiment, the arm is not attached to the mounting plate 12b by the bolts 41, but instead is attached using a quick release mechanism such that the arm and all parts carried by the arm 36 can be quickly detached and reattached.

Detailed description of operation and control functions of the motor are outside the scope of this disclosure. The motor may be operable by the user to initiate provision of torque to the wheel and to cease provision. The motor may be configured to provide torque under certain conditions, for example when a user is providing torque through a pedalling action.

As will be apparent to the skilled person, various modifications may be made to the embodiments described above.

In a variant embodiment, the motor 18 and an associated battery (not shown) are otherwise located on the bicycle, for example under a saddle. In this case, the motor 18 is coupled with the pinion gear 16 to drive the pinion gear 16 using a coupling mechanism. In an example a flexible drive shaft couples the drive shaft 34 of the motor 18 and the gear 16. Such a flexible drive shaft (not shown) is located in a sheath (not shown). An end of the sheath is fixedly mounted to the mounting member 12 around the hole 32a and the drive shaft within the sheath is coupled to the pinion gear 16 via the hole 32a. In another example, the pinion gear 16 is coupled to a gear on the opposite side of the mounting member 12 to the pinion gear 16, via the hole 32a. A drive shaft (flexible or otherwise) extends from the motor 16 to drive the gear and thus the pinion gear 16. The gear may be a bevel gear, allowing the drive shaft to arrive at the gear at a non-aligned angle, but is not limited to being of any particular type.

The pinion gear 16 is not limited to being any particular kind of gear.

In embodiments, the annular bearing assembly 14 may be absent. In this case a similar low friction arrangement may be provided fixing together the drive member 10 and the mounting member, but allowing independent rotation.

As an alternative to the internal gear and the pinion gear 16, other gear arrangements may be used. Referring to Figure 15, in an alternative embodiment parts functionally corresponding to those of the embodiment described in relation to Figures 1 to 14 are given the same reference number incremented by 200. The internal gear 10d is absent and instead a gear is provided on the exterior of the first cylindrical wall 210b, that is, teeth 210d are provided on the exterior surface thereof. An exterior surface of the bearing assembly is shaped and located flush against an interior surface of the second cylindrical wall 210e of the drive member 210. The annular portion (not shown) of the mounting member 212 is configured and located to fit flush against an interior surface of an annular bearing assembly (not shown) and to be fixed thereto.

In another variant embodiments, a ratchet may be provided on the annular back plate 10c extending circumferentially around the hub axis. In place of the pinion gear 16, a bevel gear may be provided to engage with the ratchet.

In other embodiments, instead of the internal gear 12c, a spur gear may be provided elsewhere fixed to the drive member 12, or formed integrally therewith, to rotate coaxially with the drive member 12 about the hub axis, and the pinion gear 16 mounted to drive rotation of the spur gear. In a variant, the drive member may include teeth of a spur gear around a periphery thereof and the pinion gear 16 may be mounted to drive rotation of such a spur gear and thus the drive member. Other designs for linking a drive shaft of a motor to a drive member are disclosed in US9359040 and embodiments in accordance with the present invention may incorporate such designs.

Embodiments of the invention are not limited to any particular way in which the drive shaft of the drive unit is linked to the drive member to drive rotation of the drive member about the hub axis. A friction drive or a belt drive arrangement may also be used in alternatives.

Referring to Figures 16 to 17, in an embodiment apparatus for a drive system includes a belt drive arrangement to drive rotation of a drive member in place of the pinion gear 16 and the internal gear 14. Parts functionally corresponding to those of the embodiment described in relation to Figures 1 to 14 are given the same reference number incremented by 300.

Like in that embodiment, the mounting member 312 is mounted on the first cylindrical wall 310b of the drive member 310 so as to be independently rotatable with respect to the drive member 310 about the hub axis. On a side of a drive member 310 remote from the mounting member 312, the drive member 310 includes a first pulley wheel 310c, functionally replacing the internal gear 14. A portion 337 of the arm 336 of the rotation prevention assembly is shaped to extend beyond an outer circumference of drive member 310. The portion 337 has a hole (not shown) therein through which the drive shaft of the motor 318 extends. A second pulley wheel 316 that functionally replace the pinion 16 is mounted with the end of the drive shaft so as to be in the same plane as the first pulley wheel 310c with the axis of each of the first and second pulley wheels 310c, 316 being parallel. Details of how the motor 318 is attached to the arm 336 are not shown; the motor 318 may be attached with bolts through aligned holes in the arm and housing of the motor 318, like in the embodiment of Figures 1 to 14. The drive system includes a belt 317 and the first and second pulley wheels 310c and 316 are coupled by the belt. The motor 318 drives rotation of the second pulley wheel 316 and the rotation of the second pulley wheel 316 drives rotation of the first pulley wheel 310c.

In a variant, the second pulley wheel 316 is rotatably mounted on the portion 337 of the arm 336 and includes a keyway into which the drive shaft of the motor 318 can engage. This facilitates detachment and attached of the motor 318 from the second pulley wheel 316.

As another variant to the embodiment shown in Figures 16 to 17, the first and second pulley wheels 310a, 316 and the belt 317 may be replaced with mated gears. As a further variant, the first and second pulley wheels 210a, 216 may be replaced with first and second cogs and the belt replaced with a chain.

In a still further embodiment, the arm 36 may be hingedly mounted on the mounting member 12, and arranged to abut the chainstay when opened. The arm 36 may be folded away when required and secured in place with a clip.

In the preferred embodiment the motor 18 and rotation prevention assembly 15 may be removable by unscrewing mounting bolts 41. This is shown in particular in Figures 9 and 10. An opening of a pinion shaft socket 300 is shown, configured to accept the motor shaft 34 when electric drive is required (optionally by means of a keyway, as mentioned above). In this configuration, all parts mounted on the mounting member 12 may freely rotate around the hub 22. No anti-rotation features are present; thus mounting member 12 and pinion gear 16 may freely rotate in synchronicity with drive member 10 allowing the rider to cycle without extra frictional impairment, in case any were to be present.

The drive system may be provided as a kit for retrofitting to a wheel of a bicycle.

Where a hub 22 does not permit the drive member 12 to be attached to it, for some applications the drive member may be configured to attach to one or more spokes of a wheel. As already mentioned, the drive system may be used with a wheelchair or a golf trolley, or wheel of any kind, including wheels of a tricycle or wheelbarrow or other type of trolley. For example, wheels of a golf trolley commonly have three to six plastic spokes and the skilled person may easily configure the drive member to attach to such spokes so as to drive rotation of the wheel. Golf trolleys commonly have three wheels with a single wheel at a front of the trolley and two at the rear. In this case, the drive system may be mounted to drive rotation of the front wheel.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

Unless otherwise stated, all individual features and/or steps of all embodiments described herein are disclosed in isolation and any combination of two or more such features is also disclosed, to the extent that such features or steps or combinations of features and/or steps are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features

Claims

CLAIMS1. Apparatus for connecting a drive unit to a wheel to enable the drive unit to drive rotation of the wheel about a central axis of the wheel, comprising: a drive member for mounting to the wheel such that rotation of the drive member about the central axis drives rotation of the hub about the central axis; a mounting member mounted on the drive member and rotatably independent of the drive member with respect to the central axis; a drive element having a drive element axis that is fixedly disposed in relation to the mounting member, and for coupling to the drive unit such that the drive unit can drive rotation of the drive element about the drive element axis; preventing means for preventing rotation of the mounting member about the central axis; wherein the drive member includes coupling means for coupling with the drive element, so that the rotation of the drive element drives rotation of the drive member, wherein the drive member has a first side for facing away from the wheel when the drive member is mounted on the wheel, and wherein the coupling means and the drive element are at least partially located in a recessed region in the first side.
2. The apparatus of claim 1, wherein the mounting member is mounted on the drive member so that, when the drive member is mounted on the wheel, the drive member is located between the mounting member and spokes of the wheel
3. The apparatus of claim 1 or claim 2, wherein an outward facing surface of the first side of the drive member is planar.
4. The apparatus of claim 1, wherein the coupling means and the drive element are coupled in the recessed region.
5. The apparatus of any one of the preceding claims, wherein the drive member comprises at least one cylindrical wall extending circumferentially around the central axis, on which the coupling means is mounted.
6. The apparatus of any one of the preceding claims, wherein the drive element comprises a first gear and the coupling means comprises a second gear for engaging with the first gear so that rotation of the first gear drives rotation of the drive member.
7. The apparatus of claim 6, wherein the second gear is an internal gear extending around the central axis, with teeth projecting inwardly.
8. The apparatus of claim 6, wherein the second gear extend around the central axis, with teeth projecting outwardly.
9. The apparatus of any one of the preceding claims, further comprising a bearing assembly, wherein the drive member and the mounting member are each fixed to the bearing assembly enabling the mounting member to be rotatably independent of the drive member with respect to the central axis.
10. The apparatus of any one of the preceding claims, wherein the first gear is mounted on the mounting member.
11. The apparatus of any one of the preceding claims, wherein the mounting member extends across the recessed region, substantially covering an open side of the recessed region.
12. The apparatus of any one of the preceding claims, wherein the wheel includes rotor disc mounting means on the hub and wherein the rotor disc mounting means is suitable for attachment of a rotor disc of a disc braking system, wherein the drive member comprises means for mounting to rotor disc mounting means on the hub, and the drive member is for mounting in place of the rotor disc.
13. The apparatus of claim 12 when dependent on claim 2, wherein the drive member includes a radially extending annular rotor disc portion configured for use with a calliper mechanism of a disc braking system, wherein the planar surface comprises the outward surface of the annular rotor disc portion.
14. The apparatus of any one of the preceding claims, wherein the preventing means is mounted, directly or otherwise, on the mounting member.
15. The apparatus of claim 14, wherein the preventing means is shaped to abut against a frame member supporting the wheel when the mounting member is rotated.
16. The apparatus of claim 1401 claim 15, wherein the preventing means is provided as a housing for the drive unit.
17. The apparatus of claim 14 or claim 15, wherein the preventing means is configured to attach to a frame member supporting the wheel when the mounting member is rotated.
18. The apparatus of any one of the preceding claims, further comprising the drive unit, wherein the drive unit is mounted, directly or indirectly, on the mounting member.
19. The apparatus of claim 18, wherein the drive unit is mounted on the mounting member such that a mass of the drive unit can be entirely carried by mounting member.
20. The apparatus of claim 18 or claim 19, wherein the drive unit is mounted on the preventing means, and wherein the preventing means is mounted on the mounting member.
21. The apparatus of any one of claims 18 or 20, wherein the drive unit is detachable, such that a drive shaft thereof is separable from the first gear and the drive unit is separable from the mounting member.
22. A wheel comprising the apparatus of any one of the preceding claims, the apparatus being mounted on a hub of the wheel.
23. A method of connecting a drive unit to a wheel to enable the drive unit to drive rotation of the wheel about a central axis of the wheel, comprising: mounting the apparatus of any one of the preceding claims onto a wheel; coupling the drive element to the drive unit.
24. The method of claim 23, wherein the mounting comprises attaching the drive member to rotor disc mounting means of the hub of the wheel in place of a disc rotor.